On 07/20/11 15:46, Eric Blake wrote: > On 07/20/2011 07:25 AM, Jes Sorensen wrote: >>> I think if libvirt wants qemu to use an fd instead of a file name, it >>> shouldn't pass a file name but an fd in the first place. Which means >>> that the two that we need are support for an fd: protocol (patches on >>> the list, need review), and a way for libvirt to override the backing >>> file of an image. >> >> The problem is that QEMU will find backing file file names inside the >> images which it will be unable to open. How do you suggest we get around >> that? > > We've already told you - qemu must have a way to be passed fds which are > associated with names, and when a file refers to another backing file by > name, then qemu falls back on its fd/name mapping to use the > already-passed fd instead. Which implies that someone else, either > libvirt or a qemu-maintained libblockformat.so, needs to have a stable > interface for parsing the backing file name out of an arbitrary qcow2 > file, and that this interface must work no matter how many other > extensions are added to qcow2. As I replied to you earlier, libvirt is *not* allowed to be messing with internals of image files! Passing in backing file fds as a result of libvirt messing around in internals of the image headers is utterly broken and is not going to happen! Jes -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list